The concept of a perceptual noise exclusion deficit is an emerging

hypothesis A hypothesis (: hypotheses) is a proposed explanation for a phenomenon. A scientific hypothesis must be based on observations and make a testable and reproducible prediction about reality, in a process beginning with an educated guess o ...

as to the origins and nature of

dyslexia Dyslexia (), previously known as word blindness, is a learning disability that affects either reading or writing. Different people are affected to different degrees. Problems may include difficulties in spelling words, reading quickly, wri ...

. It is supported by research showing that dyslexic adults and children experience difficulty in targeting visual

information Information is an Abstraction, abstract concept that refers to something which has the power Communication, to inform. At the most fundamental level, it pertains to the Interpretation (philosophy), interpretation (perhaps Interpretation (log ...

in the presence of visual perceptual distractions, but subjects do not show the same impairment when the distracting factors are removed in an experimental setting. Thus, some dyslexic symptoms appear to arise because of an impaired ability to filter out environmental distractions, and to categorize information so as to distinguish the important sensory data from the irrelevant. The new research shows that differences in processing ability between dyslexic and non-dyslexic subjects for visual

data Data ( , ) are a collection of discrete or continuous values that convey information, describing the quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted for ...

occurs only in when there are environmental distractions. When the visual distractions were removed, the dyslexic subjects showed no sign of impairment. Further, exposure to external visual noise produced the same level of impairment in dyslexic subjects regardless of the speed of the task being tested. The researchers have also found that dyslexic children and adults have difficulty forming perceptual categories, such as those involved in distinguishing printed letters and

speech sounds "Speech Sounds" is a science fiction short story by American writer Octavia E. Butler. It was first published in ''Asimov's Science Fiction Magazine'' in 1983. It won Butler her first Hugo Award for Best Short Story in 1984. The story was subs ...

, or in deducing rules for sorting of geometrical shapes. This difficulty appears to be closely related to the difficulty with filtering ambient data and focusing on relevant factors while disregarding irrelevant distractors. External noise interferes with the ability of dyslexic subjects to recognize

patterns A pattern is a regularity in the world, in human-made design, or in abstract ideas. As such, the elements of a pattern repeat in a predictable manner. A geometric pattern is a kind of pattern formed of geometric shapes and typically repeated li ...

; the lack of a pattern-based template for interpretation of

sensory information A sense is a biological system used by an organism for sensation, the process of gathering information about the surroundings through the detection of stimuli. Although, in some cultures, five human senses were traditionally identified as su ...

in turn may make it difficult to judge the relative importance and relevancy of details as they are perceived. The presence a perceptual noise exclusion deficit has been further demonstrated in the auditory domain. Researchers found a speech perception deficit in dyslexic subjects which was present in noise but absent in silence. This hypothesis is supported by a study showing dyslexic subjects in comparison to non-dyslexic subjects in the research sample were less responsive to cueing in a visual discrimination task, suggesting that the dyslexics had greater difficulty than controls with prioritizing certain visual information based on previous exposure. The researchers also found that performance on the cueing task could be a more accurate means of discerning dyslexic from normal readers in comparison to the range of other psychophysical tasks typically used in

dyslexia research Dyslexia is a reading disorder wherein an individual experiences trouble with reading. Individuals with dyslexia have normal levels of intelligence but can exhibit difficulties with spelling, reading fluency, pronunciation, "sounding out" words, wr ...

References

{{Dyslexia Theories of dyslexia

See also

References